Method of manufacturing piston rings



March 15, 1932. M. OKOCHI ET AL 1,349,457

METHOD OF MANUFACTURING PISTON RINGS I, rg g 1& firmruz: 1:27.2 I,

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March 15, 1932. M. OKOCHI ET AL METHOD OF MANUFACTURING PI'STON R-I'NGS Filed April ,l9 192 4 Sheets-Sheet 2 777. Okoc/n anf M. OKOCHI ET 'AL March 15, 19 2.

March 15, 1932. OKOCH! ET AL 9 4 METHOD OF'MANUFACTURING PISTON RINGS Filed April 19. 192 4 Sheets-Sheet 4 K. [Him/a.

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PATENT OFFICE;

KEIKICHI EBIHABA, OF KOISHIKAWA-KU,

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JAPAN METHOD OF MANUFACTURING- PISTON' RINGS Application flled lptril 18, 1827, Serial ll'o. 185,01, and in Tapan Kay 18, 1926.

This invention relates to piston rings exerting uniformly I distributed a pressure against the wall of an engine cylinder and .also a method of manufacturing the same.

I; The object of the invention is a new method of manufacturing such piston rings, especially suitable for mass production, in a simple and easy manner.

The drawings illustrate how the invention 10 is to be carried out, and in which Fig. 1 shows a cylindrical 'blank having a longitudinal opening, an example of one form of blank to be used in this method; Fig. 2 shows an end view thereof; Fig. 3 shows an end view 18 of the cylindrical blank .closed by a magnetic chuck; Fig. 4 shows a longitudinal sec: tion of a series of blank rings closed by a magnetic chuck; 'Fig. 5 shows one form of .finished in which 'A is the plan, B the a elevation; .ig. 6 shows another example of a-finished ring, in whichA is the plan, B an elevation; Fig. 6' shows a ring blank having iail:1i opening to illustrate the efiect of the s 25 form 0 the cylindrical blank, in which A is a plan, B anelevation Figs. -8 and 9 illustrate steps of a convenient method of preparing the modified blank ring, and in WhlCh F' 8 illustrates the firststep thereof; A andB I0 ing side and Ian views; Fig. 9 illustrates the second step t ereof; A and B being side and plan views; Fig. 10 showsthe prexure dis 7 tributing curve of a piston ring according to invention acting upon the inner wall of an enginecylinder, while Figs. 11 to 15 show the pressure distributing curves of the piston rings manufactured by usual method Figs. 16 and 17 showrespectively pressure curves of a single and a compound ring manufacrding to this invention. In Fig. 1,1 is a cylindrical blank from which piston rings are manufactured according to this invention. .1' is a longitudinal opening in the blank, the side walls of which are of zigformation, the extendingel to the longitudmal ms of the hlan .In the manufacture of the a cylindrical blank is chosen that is of some what greater diameter than the ditmeter of operation; ig. 7 shows a modified the cylinder of an engine in which the rin is to be used. Then the opening 1 is forme and the zig-zag wall is so arranged that the recesses in one side face the projection of the other side, so that when closed by means of the magnetic chuck as hereafter described, they can interfit with each other to make a completely closed cylindrical blank.

The form of the longitudinal opening of the blank is by no means the essential of the invention and it may be in the form of "a longitudinal cuttin having practically parallel walls which, w en the opening is closed,

- will tightly abut against each other.

Now referrin to Fig. 3, 1 is a blank annular cylinder whlch is open at 1. 4 is a series of electro-magnets having north poles 2 at their outer ends. 5 is another series of electro-magnets arran d alternatel to the electro-magnets 4 an having sout poles-3 at 70 their outer ends. This forms two series of. electro-magnets having opposite polarity which are alternately arranged in radial d1- rections and at equiangular distances along the inner periphery of the blank c linder 1. Each of the electro-magnets is ed to a common shaft 6 of magnetic material at its inner. edge; this arrangement constitutes a: magnetic chuck. The magnetic force of each of the electro-magnets is adjusted to be the same so that the will each attract the blank linder inwardly to close the opening 1' with t e same attracting force and therefore the blank will be put in a condition the same as i they were compressed by .a uniformly distributed force act' upon the outer riphery .of the bl cylinder. After t e outer surface of the blank cylinder thus closed by the magnetic chuck is finished to a desired diameter by a machine such as a lathe or a grinder, the circuit of coils of the electro-magnets is cut and the blank c linder can be-easily taken of the magneticc uck and cut transversely in planes per-P pendicular to its axis into of any desired breadth by convenientmeans. Such ringscan be directly used as piston rings and they exgrt a upon the mnerw o anengme-cy er.. yarrang-. ing the electro-magnets onthe shaft 6 sothat It is to be understood that instead of a" hollow cylinder having a longitudinal opening parallel to the axis thereof a series of blank rings each having a similar opening can be used as shown in Fig. 4. In this case, the operation is quite the same as above described, and the rings can be finished to a desired diameter after the opening is closed by the magnetic chuck.

In the actual working of the invention, if the cylindrical blank is accurately cylindrical, it is slightly deformed into an oval form as shown in Fi 6' when the opening of the blank is closed y the uniform internal attraction by the said magnetic chuck. As the outer wall of such oval cylinder is turned into true cylinder, the material taken off is greater in parts h, 7:. than in parts g, g. Therefore, when the piston rings are made of a truly cylindrical blank, they may be of varying thicknesses. In order toavoid such a defect, the cylindrical or ring blank is preferably made somewhat deformed from true cylindrical form. Referring to Fig. 7 which s ows an example of such a blank from which piston rings are to be made for an engine cylinder of 127 mms. inner diameter and in which Q=R=67.0 mms.

Distance between 0 and 0 or 0 and O 2.0 mms.

' Distance between 0 and 0 31) mms.

Therefore, D is greater than. D so that the form of the blankbecomes slightly ellip tical. The original thickness of the blank was 5 mms. which .can be milled or ground down to 4 mms.

- One of the simplest manners of forming a special cylindrical or ring blank of slightly elliptic form, as described with reference to Fig. 7, is to first manufacture a standard finished ring .of uniform thickness from the same material as that of which the blank is to be made. This finished ring will have a slightly elliptical form when it is freed from any pressure closing the opening. Referring to Figs. 8 and 9, such a finished ring 7 of uniform thickness is clamped between-two discs 8, 8 by means of bolts and nuts 9, so

that no deformation of the rin 'iscaused.

thereby. By using the outline 0 such fixed ring as a model, a model plate 10 of exactly thef'same size and shape thereto is manufactured and finally by using such, model plate 10, the cylindrical or ring blank is turned to thesamesection as that of the nioglel'phte by'a suitable machine of known manufacturing piston which the ring is to be formed by means of a magnetic chuck exerting uniform attracting force around the inner circumference of the blank, and to turn it to a desired outer diameter. Of course, two or more of the new rings may be couple together to build up a compound ring and in this case the position of the openings of each rin are preferably displaced relative to each 0t er.

Fig. 10 shows a pressure distribution curve of a piston rin accordin to the present in- While vention, ig. 11 to ig. 15 show those of piston rings of usual manufacture, the curves being obtained by use of a device for measuring piston ring pressure, and applied for U. S. patent application filed on 3rd of August, 1926, Serial No. 126,917. It will be clearly understood that the new piston ring exerts practically uniformly distributed pressure against the-wall of the engine cylinder while piston rings manufactured by the usual process, exert very unequal pressure, the value of which greatly varies to the points of the peripherical run. Fig. 17 shows another example of a pressure distribution of a compound ring manufactured by the methodv of this invention, which is so arran ed that the pressure curve of each ring mutua ly compensates possible unevenness of the pressure of each ring, to completely give uniform pressure as shown in Fig. 16. Briefly, the invention consists of a new idea of. closing an opened cylindrical blank or opened ringblank by means ofa magnetic chuck so that the closing force employed and acting at the circumference of the blank 1s absolutely uniform. Under such condition the'blanks are turned into the true cylindrical surface of the blank which fits against the inner wall of an engine cylinder, when closed by the cylindrical wall of the engine cyl1nder, the condition therein becomes quite the same as when closed by the magnetic chuck so that they exert uniform pressure against the engine cylinder. Claims.

- 1. A process for making piston rings for cylinders of known diameter comprising forming a noncontinuous annular metal blank of a larger diameter than the bore of the cylinder, distorting such blank to a noncircular form, such that when the blank 1s compressed to close the opening there n a true circular annulus is formed, compressing said blank by equal forces exerted in radial directions of the blank throughout its extent,

holding the blank in such compressed condition and milling the outer surface of said blank when so held to the proper size.

2. A process as claimed in claim 1 in which the non-circular form of the blank is that of an ellipse. 1

In testimony whereof we aflix our sign tures.

MASATOSI OKOCHI. KEIKICHI EBIHARAQ 

